A rubber blend containing at least one functionalized synthetic rubber and at least one ethoxylated alcohol

Abstract

The present invention relates to a rubber blend suitable for producing a vulcanized product which, in addition to a filler and a crosslinking agent, contains 50 to 100 phr of at least one functionalized synthetic rubber and 0.5 to 20 phr of at least one ethoxylated compound of formula (I): RO(CH2CH2O) x H (wherein R represents an alkyl, the alkyl may be branched or unbranched, and x represents a rational number from 1 to 25) and has a low rolling resistance.

Description

Technical Field

[0001] The present invention relates to a novel rubber mixture containing at least one functionalized synthetic rubber and at least one ethoxylated compound of formula (I), a process for its production, its use for producing rubber vulcanizates, the corresponding vulcanizates, and the use of at least one functionalized synthetic rubber and at least one ethoxylated compound of formula (I) in rubber mixtures, vulcanizates and shaped articles obtained therefrom for reducing the rolling resistance of shaped articles, preferably tires.

Background Art

[0002] The EU has an obligation to reduce its greenhouse gas emissions and achieve climate neutrality by 2050. Reducing CO2 emissions from road traffic plays a major role in achieving these goals.

[0003] The new EU tire labeling system came into force on May 1, 2021 and is based on three important tire characteristics: rolling resistance - and thus fuel efficiency -, wet grip and external vehicle noise. With the new EU tire label, consumers will be able to actively choose more fuel-efficient tires.

[0004] More fuel-efficient tires contribute to reducing emissions in road traffic. Depending on the rolling resistance of the tire, the fuel efficiency can range from class A (best fuel efficiency) to class E. Fuel consumption is important from both an economic and an environmental perspective. Low fuel consumption has a positive effect on the CO2 balance of vehicles, especially large commercial vehicles.

[0005] Against this background, tire manufacturers are looking for an economic way to achieve the A-class fuel efficiency target for tires.

[0006] The use of silica-containing rubber mixtures for the manufacture of passenger car tire treads is known. Silica contributes to a good combination of properties including rolling resistance, wet grip and abrasion required for passenger car tire treads. In order to obtain the desired combination of properties, the silica must be efficiently dispersed in the rubber mixture and optimally bonded to the rubber matrix during vulcanization.

[0007] To improve the processability of silica-containing rubber mixtures, it is possible to utilize additional additives such as fatty acid esters, fatty acid salts or mineral oils. The above-mentioned additives have the disadvantage of increasing fluidity but at the same time decreasing the stress values at higher elongations (e.g., 100% - 300%) or decreasing the hardness of the vulcanizate, thus adversely affecting the reinforcing effect of the filler. However, insufficient hardness or rigidity of the vulcanizate results in insufficient operating characteristics of the tire, especially during cornering. Furthermore, overly low hardness leads to increased abrasion of the vulcanizate by the road surface, thus increasing the proportion of so-called "microplastics" in the environment. Tire wear particles are a major source of microplastics in rivers and lakes and account for approximately 28 percent of the plastic particles in the ocean.

[0008] The loss factor tanδ gives an important indication for evaluating the rolling resistance. The lower the loss factor tanδ, the lower the rolling resistance. The loss factor tanδ must be as low as possible between 60 °C and 70 °C: less than 0.2 according to (Patent Document 1) and less than 0.12 according to (Patent Document 2).

[0009] (Patent Document 2) discloses that a rubber mixture containing 1 phr of 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane (CAS No.: 151900-44-6) and 1 phr of a specific sulfur-containing additive results in a vulcanizate having good dynamic properties, good hardness / rigidity, good rolling resistance, and low wear. The drawback is that the scorch time (t5) during the vulcanization of this rubber mixture is significantly reduced, which is a major drawback in terms of processing reliability. From the perspective of the rubber processing industry, it is more convenient to use only a few mixture components.

[0010] (In Patent Document 3), the rolling resistance is reduced by adding a specific organosilicon polysulfide. The results in Table 2 of (Patent Document 3) show that 1 phr of organosilicon polysulfide reduces the loss factor (tanδ at 60°C) by more than 10 percent. Mechanical properties such as tensile strength, elongation at break, and 300 modulus remained virtually unchanged. Here too, the drawback is that the addition of organosilicon polysulfide dramatically reduces the scorch time.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Means for Solving the Problems

[0012] Accordingly, an object of the present invention is to provide an improved rubber mixture based on a hydroxyl-containing oxide filler, which overcomes the above-mentioned drawbacks and results in a vulcanizate and a shaped article produced therefrom, such as a tire tread, having unchanged or improved properties such as 300 modulus, elongation at break and hardness, and preferably a low rolling resistance measured by the loss factor tan δ at 60° C. at a measurement frequency of 10 Hz. The improved rubber mixture should preferably also have a reduced total vulcanization time (t95). The improved rubber formulation should preferably have a lower DIN abrasion and thus also result in a more environmentally friendly vulcanizate.

[0013] The low loss factor tan δ at 60° C., preferably at a measurement frequency of 10 Hz, determined by dynamic damping according to DIN EN ISO 6721-1, is preferably less than 0.2, particularly preferably less than 0.12.

[0014] The scorch time t5 determined at 160° C. in accordance with ASTM D5289-95 is preferably in the range of 70 to 150 seconds, particularly preferably in the range of 85 to 140 seconds.

[0015] The short total vulcanization time t95 (95% conversion time) determined at a temperature of 160° C. in accordance with ASTM D5289-95 is preferably in the range of 800 to 1300 seconds, particularly preferably in the range of 900 to 1200 seconds.

[0016] The Mooney viscosity ML 1+4 determined at 100° C. in accordance with ASTM D1646 is preferably in the range of 30 to 100 MU, particularly preferably in the range of 50 to 90 MU.

[0017] A high 300 modulus value is also advantageous for the vulcanizate, especially for the tire tread. The 300 modulus (determined in accordance with DIN 53504) is preferably 8 to 20 MPa, particularly preferably 9.5 to 20 MPa.

[0018] The hardness determined in accordance with DIN53505 is preferably in the range of 55 to 70 Shore A.

[0019] The DIN abrasion determined in accordance with ASTM D5963 should preferably be low, particularly preferably less than 120 mm 3 and very particularly preferably less than 110 mm. 3 is.

[0020] The following unit “phr” represents parts by weight relative to 100 parts by weight of the total amount of rubber present in the rubber mixture, i.e., the total amount of functionalized and non-functionalized synthetic rubber and natural rubber.

[0021] Surprisingly, the above object is achieved by - at least one functionalized synthetic rubber in the range of 50 to 100 phr, preferably a functionalized BR rubber and / or a functionalized SBR rubber, - at least one natural rubber and / or non-functionalized synthetic rubber in the range of 0 to 50 phr, - at least one hydroxyl-containing oxide filler in the range of 0.1 to 250 phr, - at least one carbon black in the range of 0 to 120 phr, preferably 0.1 to 100 phr, - at least one crosslinking agent selected preferably from the group of sulfur donors and / or sulfur in the range of 0.1 to 20 phr, and at least one ethoxylated compound of formula (I) in the range of 0.5 to 20 phr RO(CH2CH2O) x H (I), (wherein R represents an alkyl, where the alkyl may be branched or unbranched, and x represents a rational number from 1 to 25) is achieved by the rubber mixture according to the invention containing.

[0022] The vulcanizate according to the invention obtained by vulcanizing the rubber mixture according to the invention surprisingly retains equally good performance characteristics such as elongation at break, hardness and vulcanization characteristics, while having a low loss factor tanδ at 60 °C, an improved 300 modulus, a reduced Mooney viscosity, a short full vulcanization time (t95) and a sufficiently long scorch time (t5).

Mode for Carrying Out the Invention

[0023] Rubber The rubber mixture according to the invention preferably contains at least one functionalized synthetic rubber selected from the group consisting of polar and non-polar functionalized synthetic rubbers.

[0024] The functionalized synthetic rubber in the context of the present invention is substituted with one or more functional groups selected from carboxyl groups, mercaptan groups, alkoxysilane groups, siloxane groups, hydroxyl groups, ethoxy groups, epoxy groups, amino groups, phthalocyanine groups, silane-sulfide groups and metal atom-containing groups, preferably at the main chain and / or at the end groups, particularly preferably selected from mercaptan groups, alkoxysilane groups and hydroxyl groups, very particularly preferably selected from mercaptan groups and alkoxysilane groups, and is understood to mean a synthetic rubber thus substituted.

[0025] Preferred polar and non-polar functionalized synthetic rubbers are functionalized BR - polybutadiene ABR - butadiene / C1 - C4 - alkyl acrylate copolymer CR - polychloroprene IR - polyisoprene SBR - styrene / butadiene copolymer having a styrene content of 1 to 60% by weight, preferably 20 to 50% by weight, IIR - isobutylene / isoprene copolymer NBR - butadiene / acrylonitrile copolymer having an acrylonitrile content of 5 to 60% by weight, preferably 10 to 50% by weight, HNBR - partially or fully hydrogenated NBR rubber EPDM - Ethylene / Propylene / Diene Copolymer SIBR - Styrene - Isoprene - Butadiene Rubber ENR - Epoxidized Natural Rubber SNBR - Acrylonitrile - Styrene / Butadiene Rubber HNBR - Hydrogenated Acrylonitrile / Butadiene Rubber XNBR - Carboxylated Acrylonitrile / Butadiene Rubber HXNBR - Hydrogenated Carboxylated Acrylonitrile / Butadiene Rubber

[0026] At least one functionalized synthetic rubber is preferably selected from the group consisting of functionalized SBR rubber, functionalized BR rubber, and functionalized IR rubber, particularly preferably selected from functionalized SBR rubber and functionalized BR rubber.

[0027] It is preferred when the rubber mixture according to the invention contains at least one functionalized SBR rubber and / or functionalized BR rubber, particularly preferably at least one functionalized SBR rubber and at least one functionalized BR rubber.

[0028] It is preferred when at least one functionalized SBR rubber is substituted by one or more functional groups selected, in particular, from mercaptan groups, alkoxysilane groups, and hydroxy groups, especially preferably by two or more functional groups which are mercaptan groups and alkoxysilane groups, in the main chain and / or at the end groups. It is preferred when at least one functionalized SBR rubber is Trinseo's SPRINTAN® SLR 3402.

[0029] The functionalized SBR rubber can be solution - polymerized styrene - butadiene rubber (SSBR) or emulsion - polymerized styrene - butadiene rubber (ESBR), and it is also possible to utilize a mixture of at least one functionalized SSBR and at least one functionalized ESBR.

[0030] The molar weight (Mw) of the styrene-butadiene copolymer can vary over a wide range. Styrene-butadiene copolymers having an Mw of 250,000 to 600,000 g / mol, particularly preferably having an Mw of 350,000 to 500,000 g / mol, are preferred.

[0031] At least one functionalized BR rubber is preferably substituted, in the main chain and / or at the end groups, by one or more functional groups selected from mercaptan groups, alkoxysilane groups and hydroxy groups, particularly preferably by alkoxysilane groups. At least one functionalized BR rubber is preferably Zeon's NIPOL® BR 1261.

[0032] The molar weight of the butadiene polymer can vary over a wide range. Butadiene polymers having an Mw of 250,000 to 500,000 g / mol are preferred.

[0033] Polybutadiene having a cis content of 90 wt% or more is called high cis, and polybutadiene having a cis content of less than 90 wt% is called low cis. An example of low cis polybutadiene is Li-BR (butadiene rubber by a lithium catalyst) having a cis content of 20 wt% to 50 wt%. In the context of the present invention, high cis functionalized BR rubbers are preferred.

[0034] The rubber mixture according to the present invention contains 50 to 100 phr, preferably 70 to 100 phr of at least one functionalized synthetic rubber.

[0035] The rubber mixture according to the present invention preferably contains at least one functionalized SBR and at least one functionalized BR rubber in a weight ratio of SBR:BR of 100:0 to 0:100, particularly preferably 90:10 to 10:90, very particularly preferably 90:10 to 30:70, and very, very particularly preferably 80:20 to 50:50.

[0036] In addition to the above-mentioned functionalized synthetic rubber, the rubber mixture of the present invention may also contain at least one non-functionalized synthetic rubber and / or at least one natural rubber. The above-described embodiments regarding the functionalized synthetic rubber still apply, except that in the case of the non-functionalized synthetic rubber, the rubber is not functionalized.

[0037] The rubber mixture of the present invention may contain 0 to 50 phr, preferably 0 to 30 phr of at least one non-functionalized synthetic rubber and / or at least one natural rubber.

[0038] The ethoxylated compound of formula (I) The rubber mixture according to the present invention contains at least one ethoxylated compound of formula (I). RO(CH2CH2O) x H (I), (wherein, R represents an alkyl, where the alkyl may be branched or unbranched, and x represents a rational number from 1 to 20).

[0039] R is preferably C1-C 20 -alkyl, particularly preferably C5-C 17 -alkyl, very particularly preferably C 10 ~C 15 -alkyl, very very particularly preferably iso-C 13 -alkyl, most preferably iso-C 13 H 27 represents.

[0040] x preferably represents a rational number from 2 to 22, particularly preferably from 4 to 20.

[0041] At least one ethoxylated compound of formula (I) is present, for example, in Sasol's MARLIPAL® O 13 / 50.

[0042] The rubber mixture according to the invention generally contains at least one ethoxylated compound of formula (I) in an amount of 0.5 to 20.0 phr, preferably 1.0 to 15.0 phr, particularly preferably 2.0 to 12.0 phr and very particularly preferably 4.0 to 11.0 phr.

[0043] Filler At least one hydroxyl-containing oxide filler is preferably selected from the group consisting of silica, synthetic silicates and natural silicates.

[0044] The content of the hydroxyl-containing oxide filler in the rubber mixture according to the invention is 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr and very particularly preferably 30 to 160 phr.

[0045] Suitable hydroxyl-containing oxide fillers are preferably selected from the following group - In particular, silica having a specific surface area (BET) of 5 to 1000, preferably 20 to 400 m2 / g and preferably having a primary particle size of 100 to 400 nm, which may optionally be present as a mixed oxide with other metal oxides such as Al, Mg, Ca, Ba, Zr, Ti oxides, etc. - Synthetic silicates such as alkaline earth metal silicates such as aluminum silicate, magnesium silicate or calcium silicate, etc., having a specific surface area (BET) of 20 to 400 m2 / g and preferably having a primary particle size of 10 to 400 nm. And - Natural silicates such as kaolin and other naturally occurring silica. And mixtures thereof.

[0046] The above BET surface area is determined in accordance with DIN ISO 9277. The indicated primary particle size is based on measurements using an instrument for particle analysis using scattered light. The calculation of the particle size is based on the Mie theory that explains the interaction between light and matter (DIN / ISO 13320).

[0047] It is preferred when the silica is obtained by precipitation of a silicate solution or by flame hydrolysis of silicon halide.

[0048] It is preferred when the rubber mixture according to the invention contains at least one hydroxyl-containing oxide filler from the group of silicas having a specific surface area (BET) in the range of 5 to 1000, preferably 20 to 400 m2 / g, in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr, very particularly preferably 30 to 160 phr.

[0049] The rubber mixture according to the invention may contain at least one carbon black as a filler.

[0050] In a preferred embodiment, the rubber mixture according to the invention contains at least one carbon black as a filler.

[0051] The rubber mixture of the invention preferably contains at least one carbon black in an amount of 0.1 to 120 phr, preferably 0.1 to 100 phr, particularly preferably 1 to 70 phr, very particularly preferably 2 to 40 phr.

[0052] Carbon black that can be obtained by the lamp black, furnace black or gas black process and has a specific surface area (BET) in the range of 20 to 200 m 2 / g, such as SAF, ISAF, IISAF, HAF, FEF or GPF carbon black, is preferred. The rubber mixture of the invention preferably contains at least one carbon black having a specific surface area (BET) in the range of 20 to 200 m 2 / g.

[0053] It is preferred when the rubber mixture according to the invention contains at least one of the above-mentioned silicas and at least one of the above-mentioned carbon blacks as fillers.

[0054] It is very particularly preferred when the rubber mixture according to the invention contains at least one of the above-mentioned silicas in an amount of 25 to 180 phr, preferably 30 to 160 phr and at least one of the above-mentioned carbon blacks in an amount of 1.0 to 70 phr, preferably 2.0 to 40 phr as fillers.

[0055] The total amount of carbon black and silica-based fillers in the rubber mixture according to the invention is preferably 26 to 250 phr, particularly preferably 32 to 200 phr.

[0056] Crosslinking agents and vulcanization accelerators The rubber mixture according to the invention may contain one or more crosslinking agents.

[0057] It is preferred when the rubber mixture according to the invention contains at least one crosslinking agent from the group of sulfur and sulfur donors.

[0058] Sulfur can be used in elemental soluble or insoluble form. It is particularly preferred when the rubber mixture according to the invention contains at least one sulfur donor and / or sulfur, very particularly preferably sulfur.

[0059] Examples of suitable sulfur donors are dimorpholyldisulfide (DTDM), 2-morpholinodithiobenzothiazole (MBSS), caprolactam disulfide, dipentamethylenethiuram tetrasulfide (DPTT), tetramethylthiuram disulfide (TMTD) and tetrabenzylthiuram disulfide (TBzTD).

[0060] The rubber mixture according to the invention generally contains at least one crosslinking agent from the group of sulfur and sulfur donors in an amount of 0.1 to 20 phr, preferably 0.5 to 10 phr, particularly preferably 1.0 to 8 phr and most preferably 1 to 4 phr.

[0061] The rubber mixture according to the invention may also contain zinc oxide. This is a complexing agent for sulfur and sulfur donors and thus facilitates the binding of sulfur to the rubber matrix.

[0062] A preferred rubber mixture according to the invention has a BET surface area of 2 to 100 m 2 / g, preferably 2 to 70 m 2 / g and contains zinc oxide. The BET surface area of the zinc oxide can be measured in accordance with DIN ISO 9277.

[0063] The zinc oxide is generally present in the rubber mixture according to the invention in an amount of 0 to 20 phr, preferably 0.1 to 10 phr, particularly preferably 1 to 5 phr.

[0064] The rubber mixture according to the invention may contain one or more vulcanization accelerators.

[0065] The rubber mixture according to the invention particularly preferably contains at least one vulcanization accelerator from the group consisting of mercaptobenzothiazole, thiocarbamate, dithiocarbamate, thiuram, thiazole, sulfenamide, thiazole sulfenamide, xanthate, bi- or polycyclic amines, thiophosphate, dithiophosphate, caprolactam, thiourea derivatives, guanidine, cyclic disulfanes and amines, in particular zinc diaminediisocyanate, hexamethylenetetramine, 1,3-bis(citraconimidomethyl)benzene, and very particularly preferably contains at least one vulcanization accelerator from the group of sulfenamides, very particularly preferably N-cyclohexylbenzothiazole sulfenamide (CAS number: 95-33-0).

[0066] The rubber mixture of the invention generally contains at least one of the mentioned vulcanization accelerators in an amount of 0.1 to 20 phr, preferably 0.5 to 10 phr and more preferably 1.0 to 5 phr.

[0067] The rubber mixture of the invention preferably contains at least one crosslinking agent and at least one vulcanization accelerator.

[0068] The rubber mixture of the present invention particularly preferably contains at least one crosslinking agent from the group of sulfur and sulfur donors, and at least one vulcanization accelerator from the group of mercaptobenzothiazole, thiazole sulfenamide, thiuram, dithiocarbamate, xanthate and thiophosphate, particularly preferably from the group of sulfenamides, and very particularly preferably N-cyclohexylbenzothiazole sulfenamide (CAS number: 95-33-0).

[0069] The rubber mixture of the present invention particularly preferably contains at least one crosslinking agent selected from the group consisting of sulfur and sulfur donors, at least one vulcanization accelerator selected from the group consisting of mercaptobenzothiazole, thiazole sulfenamide, thiuram, dithiocarbamate, xanthate and thiophosphate, particularly preferably from the group of sulfenamides, and very particularly preferably N-cyclohexylbenzothiazole-2-sulfenamide (CAS number: 95-33-0), and zinc oxide.

[0070] The total amount of the crosslinking agent and the vulcanization accelerator in the rubber mixture is preferably 1.0 to 20 phr, particularly preferably 2.0 to 13 phr.

[0071] Reinforcing additive The rubber mixture according to the present invention may contain one or more reinforcing additives.

[0072] The rubber mixture according to the present invention preferably contains at least one reinforcing additive from the group of sulfur-containing organic silanes, particularly sulfur-containing silanes containing an alkoxysilyl group and very particularly preferably sulfur-containing organic silanes containing a trialkoxysilyl group.

[0073] It is particularly preferred when the rubber mixture according to the present invention contains one or more sulfur-containing silanes from the group of bis(triethoxysilylpropyl)tetrasulfane, bis(triethoxysilylpropyl)disulfane and 3-(triethoxysilyl)-1-propanethiol.

[0074] Liquid sulfur-containing silanes can be absorbed onto a carrier (dry liquid) for better meterability and / or dispersibility. The content of sulfur-containing silanes in these "dry liquids" is preferably 30 to 70 parts by weight, particularly preferably 40 to 60 parts by weight, per 100 parts by weight of the dry liquid.

[0075] The rubber mixture according to the invention generally contains at least one reinforcing additive in an amount of 0.1 to 20 phr, preferably 0.5 to 15 phr and more preferably 1.0 to 10 phr.

[0076] Rubber auxiliaries The rubber mixture according to the invention may further contain one or more rubber auxiliaries. Examples of suitable rubber auxiliaries include anti-aging agents, binders, heat stabilizers, light stabilizers, flame retardants, processing aids, impact resistance improvers, plasticizers, tackifiers, blowing agents, dyes, pigments, waxes, extenders, organic acids such as stearic acid, retarders, especially triethanolamine, polyethylene glycol, hexanetriol, vulcanization reversion stabilizers and secondary accelerators.

[0077] These rubber auxiliaries can be added to the rubber mixture according to the invention in amounts customary for these auxiliaries and also guided by the end use of the vulcanizate produced therefrom. Customary amounts are, for example, 0.1 to 30 phr.

[0078] The rubber mixture according to the invention may contain one or more anti-aging agents. Suitable anti-aging agents are amine anti-aging agents such as diaryl-p-phenylenediamine (DTPD), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN), phenyl-β-naphthylamine (PBN), preferably those based on phenylenediamine, such as N,N'-dicyclohexyl-p-phenylenediamine (CCPD), N-isopropyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N'-phenyl-p-phenylenediamine (7PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), and phosphites such as tris(nonylphenyl) phosphite, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), methyl-2-mercaptobenzimidazole (MMBI) and zinc methyl mercaptobenzimidazole (ZMMBI) and mixtures thereof. It is particularly preferred when at least one anti-aging agent is selected from the group consisting of N,N'-dicyclohexyl-p-phenylenediamine (CCPD) and N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD).

[0079] The processing aids must be active between the rubber particles and must have counter frictional forces during mixing, plasticization and shaping. Processing aids that may be present in the rubber mixture according to the invention are all customary lubricants for plastic processing, such as oils, such as aromatic process oils, hydrocarbons such as paraffin and PE wax, aliphatic alcohols having 6 to 20 carbon atoms, ketones, carboxylic acids such as fatty acids and montanic acids, oxidized PE wax, aromatic-modified alicyclic hydrocarbon resins, metal salts of carboxylic acids, carboxamides and, for example, carboxylic acid esters with long-chain carboxylic acids as the acid component and alcohols such as ethanol, aliphatic alcohols, glycerol, ethanediol, pentaerythritol.

[0080] In order to reduce flammability and smoke generation during combustion, the rubber mixture of the present invention may contain a flame retardant. Examples of compounds used for this purpose include antimony trioxide, phosphate esters, chlorinated paraffins, aluminum hydroxide, boron compounds, zinc compounds excluding ZnO, molybdenum trioxide, ferrocene, calcium carbonate or magnesium carbonate.

[0081] Further plastics can be added to the rubber mixture of the present invention before crosslinking, and these act, for example, as polymeric processing aids or impact resistance improvers. These plastics are preferably homo- and copolymers based on ethylene, propylene, butadiene, styrene, vinyl acetate, vinyl chloride, glycidyl acrylate, glycidyl methacrylate, acrylates and methacrylates having an alcohol component of a branched or unbranched C1-C10 alcohol, with a specific mention being given to polyacrylates having the same or different alcohol groups from the group of C4-C8 alcohols, in particular butanol, hexanol, octanol and 2-ethylhexanol, and are selected from the group consisting of polymethyl methacrylate, methyl methacrylate-butyl acrylate copolymer, methyl methacrylate-butyl methacrylate copolymer, ethylene-vinyl acetate copolymer, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer.

[0082] Known binders are based on resorcinol, formaldehyde and silica, the so-called RFS direct bonding system. These direct bonding systems can be used in any desired amount of the rubber mixture according to the present invention and at any time of incorporation into the rubber mixture according to the present invention.

[0083] In silica-based rubber mixtures, typically used for tire manufacturing etc., diphenylguanidine (DPG) or structurally similar aromatic guanidines are typically used as secondary accelerators.

[0084] Those skilled in the art understand that DPG can advantageously be replaced by 1,6-bis(N,N-dibenzylthiocarbamoyldithio)hexane, which is also known under the trade name Vulcuren®. It is also possible to replace DPG with a secondary accelerator such as TBzTD (tetrabenzylthiuram disulfide) or a dithiophosphate.

[0085] The rubber mixture according to the invention generally contains at least one of the above-mentioned secondary accelerators in an amount of 0 or 0.1 to 10 phr, preferably 0.5 to 5 phr, particularly preferably 0.2 to 3.5 phr.

[0086] Particular preference is given to the rubber mixture according to the invention which contains - at least one functionalized synthetic rubber in an amount of 70 to 100 phr, preferably a functionalized BR rubber and / or a functionalized SBR rubber, - at least one natural rubber and / or a non-functionalized synthetic rubber in an amount of 0 to 30 phr, - at least one hydroxyl-containing oxide filler in an amount of 20 to 200 phr, - at least one carbon black in an amount of 0.1 to 120 phr, preferably 0.1 to 100 phr, - at least one crosslinking agent selected from the group consisting of preferably sulfur donors and / or sulfur in an amount of 0.5 to 10 phr, - zinc oxide in an amount of 0.1 to 10 phr, - at least one vulcanization accelerator from the group consisting of particularly sulfenamides in an amount of 0.5 to 10 phr, - at least one secondary accelerator in an amount of 0.1 to 10.0 phr, - at least one reinforcing additive from the group consisting of particularly sulfur-containing silanes in an amount of 0.5 to 15 phr, - rubber auxiliaries in an amount of 0.1 to 30 phr and - at least one ethoxylated compound of formula (I) in an amount of 1 to 15 phr.

[0087] The above-mentioned further preferred ranges for the individual components also apply to these preferred mixtures.

[0088] Process for producing a rubber mixture The present invention further provides a process for producing a rubber mixture according to the present invention, characterized in that the respective components are mixed in a mixing process. This preferably involves at least one functionalized synthetic rubber, optionally at least one natural rubber and / or non-functionalized synthetic rubber, and at least one ethoxylated compound of formula (I), in the presence of at least one filler, at least one crosslinking agent, optionally at least one carbon black, optionally at least one vulcanization accelerator, optionally zinc oxide, optionally at least one secondary accelerator, optionally at least one reinforcing additive, and optionally one or more of the rubber auxiliaries mentioned, with respect to each other, in the generally preferred amounts mentioned with respect to these additives, at a temperature in the range of 130 °C to 180 °C, particularly preferably 140 °C to 170 °C.

[0089] The rubber mixture according to the present invention is produced in a conventional manner in known mixing devices such as rollers, internal mixers, downstream mixing roller mills and mixing extruders, at a shear rate of 1 to 1000 seconds -1 and is produced in a conventional manner.

[0090] The production of the rubber mixture according to the present invention is preferably carried out in a three-stage mixing process. In the first mixing stage, the filler and at least one ethoxylated compound of formula (I) and optionally further rubber auxiliaries as mentioned above, preferably an anti-aging stabilizer and a secondary accelerator, are first incorporated into the rubber in an internal mixer (kneader).

[0091] The mixing temperature in the internal mixer can reach a value up to 180 °C. The mixing temperature in the internal mixer is preferably 130 °C to 180 °C, particularly preferably 140 °C to 170 °C.

[0092] Subsequently, preferably as a second step, there is a so-called post-mastication, preferably at 130 to 180 °C, particularly preferably at 160 °C. The post-mastication can be carried out, for example, in an internal mixer.

[0093] In the third mixing stage, a crosslinking agent, a vulcanization accelerator and optionally further rubber auxiliaries as described above, preferably a secondary accelerator and zinc oxide, are added to the mixture obtained from the first mixing stage. The mixing temperature in the second mixing stage is preferably 50 to 130 °C, preferably 55 to 130 °C, particularly 60 °C to 120 °C.

[0094] The addition of at least one ethoxylated compound of formula (I) can be carried out at any time during mixing, preferably in the first step of the mixing operation, at a temperature in the range of 130 °C to 180 °C, preferably at a temperature of 140 to 170 °C.

[0095] At least one ethoxylated compound of formula (I) can be used in pure form or absorbed and / or adsorbed on a carrier selected from the group consisting of inert organic or inorganic carriers, preferably natural or synthetic silicates, particularly neutral, acidic or basic silica, aluminum oxide, carbon black or zinc oxide, in the mixing process.

[0096] Bonding mixture The present invention further provides a rubber mixture according to the present invention and a bonding mixture containing at least one binder.

[0097] The bonding mixture according to the present invention preferably contains at least one binder based on resorcinol, formaldehyde and silica.

[0098] The combination of resorcinol, formaldehyde and silica is known from the prior art as an RFS direct bonding system. The bonding mixture of the present invention can contain these direct bonding systems in any amount.

[0099] The binding mixture of the present invention can be produced by a known method by mixing the rubber mixture of the present invention with at least one binder based on resorcinol, formaldehyde and silica.

[0100] In the binder, formaldehyde can be present in the form of a formaldehyde donor. Suitable formaldehyde donors include not only hexamethylenetetramine but also methylolamine derivatives.

[0101] To improve the binding, one or more components capable of forming a synthetic resin, such as phenol and / or amine and / or aldehyde or a compound that removes aldehyde, can be added to the binding mixture of the present invention.

[0102] Process for producing a rubber vulcanizate A process for producing a rubber vulcanizate, characterized in that the rubber mixture according to the present invention is heated at a temperature of 120°C to 200°C, preferably 140°C to 180°C.

[0103] The process for producing a rubber vulcanizate according to the present invention can be carried out over a wide pressure range, preferably at a pressure in the range of 10 to 200 bar.

[0104] The present invention further provides a rubber vulcanizate obtainable by vulcanizing the rubber mixture according to the present invention.

[0105] Surprisingly, the rubber vulcanizate according to the present invention has a low rolling resistance in combination with equivalent performance characteristics, especially when used in tires.

[0106] In the context of the present invention, the rolling resistance is determined by the loss factor tanδ at 60°C according to DIN EN ISO 6721-1 dynamic damping.

[0107] Molded article The vulcanizates of the present invention are suitable for the production of all types of shaped articles, such as tire parts, technical rubber articles, such as vibration damping elements, roller covers, conveyor belt covers, drive belts, spinning cops, seals, golf ball cores, and shoe soles; they are particularly suitable for the production of tires and tire parts, such as tire treads, subtreads, carcasses, tire sidewalls, reinforced sidewalls for run-flat tires, and apex mixtures. Tire treads include summer, winter, and all-season tire treads, as well as passenger car, truck, and light truck tire treads.

[0108] Preferred shaped articles are tires and tire parts containing the vulcanizates according to the present invention.

[0109] Use The present invention provides the use of at least one ethoxylated compound of formula (I) in an amount of particularly 0.5 to 20 phr, particularly preferably 1.0 to 15.0 phr, and at least one functionalized synthetic rubber in an amount of particularly 50 to 100 phr, particularly preferably 70 to 100 phr, for producing a vulcanizate having a low rolling resistance, made from a sulfur-crosslinkable rubber mixture at a vulcanization temperature of 120 °C to 200 °C.

[0110] The present invention further provides the use of at least one ethoxylated compound of formula (I) and at least one synthetic rubber in rubber mixtures, vulcanizates, and shaped articles producible therefrom for reducing the rolling resistance of shaped articles made of vulcanizates, preferably tires and tire parts.

[0111] At least one functionalized synthetic rubber, at least one natural rubber, at least one non-functionalized synthetic rubber, at least one hydroxyl-containing oxide filler, at least one carbon black, at least one crosslinking agent, at least one vulcanization accelerator, zinc oxide, at least one secondary accelerator, at least one reinforcing additive, rubber auxiliaries and at least one ethoxylated compound of formula (I), etc., are present in the rubber mixture according to the invention, and the explanations and preferred ranges given for the optionally present components apply equally, inter alia, to the disclosed processes and uses and to the vulcanizates, shaped articles and bonding mixtures.

[0112] The explanations and preferred ranges given apply equally, inter alia, to the rubber mixtures, vulcanizates, shaped articles, bonding mixtures, processes and uses according to the invention, regardless of whether they are disclosed in plural (e.g., a plurality of rubber mixtures) or singular (e.g., a rubber mixture) with respect to the above.

[0113] The present invention is illustrated by, but not limited to, the following examples.

Examples

[0114] Exemplary embodiments

[0115]

Table 1

[0116] Production of rubber vulcanizates A rubber mixture of a noninventive reference mixture was produced according to the specification of European Patent Application Publication No. 2858831A1, which represents a conventional SBR- and BR-containing rubber mixture, and Examples 1 and 2 according to the invention were produced according to the formulations specified in Table 2. The difference between the examples of the present invention and the reference mixture is that the latter contains, in addition to the functionalized synthetic rubber, MARLIPAL® O 13 / 50 and thus also the ethoxylated compound of formula (I).

[0117] The production of the rubber mixture was carried out in the following steps.

[0118] First mixing stage: · First, NIPOL® BR1261 and SPRINTAN® SLR 3402 were put into an internal mixer and mixed for about 30 seconds. · The anti-aging agents VULKANOX® 4020 and VULKANOX® HS were added and the mixture was mixed for about 30 seconds. · Half of ZEOSIL 1165MP and SI® 75 were added and the mixture was mixed for about 60 seconds. · Half of ZEOSIL 1165MP, CORAX® N 234, and also PALMERA® A9818, Vivatec 500, Escorez 5600, RHENOGRAN® DPG-80 and MARLIPAL® O 13 / 50 were added, the mixture was mixed for about 60 seconds and then rotated. Mixing was carried out until a temperature of 160 °C was reached, and then mixing was carried out at 160 °C for 4 minutes.

[0119] Simultaneously with the end of the first mixing stage, the mixed batch was put into a downstream roller mill, formed into sheets, strips, or pellets, and stored at room temperature for 24 hours. The processing temperature was 70 °C.

[0120] Second mixing stage: Subsequently, mixing was carried out in an internal mixer until a temperature of 160 °C was reached (so-called pre-mastication).

[0121] Simultaneously with the end of the second mixing stage, the mixed batch was put into a downstream roller mill and formed into sheets, strips, or pellets using the roller mill, and stored at room temperature for 24 hours.

[0122] Third mixing stage: The addition of sulfur, zinc oxide and additives such as Rhenogran® -CBS-80 was carried out in an internal mixer at 100 °C for 2 minutes.

[0123] Simultaneously with the end of the third mixing stage, the mixed batch was shaped into sheets, strips, or pellets using a roller mill and stored at room temperature for 24 hours. The processing temperature was 70 °C in this case.

[0124] The rubber mixtures 1 and 2 according to the invention show no spots on the surface, and thus, good mixing of the additives used is presumed.

[0125]

Table 2

[0126] Technical tests Vulcanizates produced at 160 °C from the rubber mixtures of Examples 1 and 2 and from the reference mixture were subjected to the technical tests specified below. The determined values are reported in Table 3.

[0127] Very good properties of the rubber mixtures / their vulcanizates were achieved when their properties were within the "preferred ranges" specified.

[0128] Tests on test specimens were carried out using the following test methods.

[0129] Mooney viscosity measurement The determination was carried out using a shear disk viscometer in accordance with ASTM D 1646. The viscosity is directly measurable during the processing of rubbers (and rubber mixtures) from the opposing forces exerted by them. In a Mooney shear disk viscometer, a grooved disk is moved in a heatable chamber at about 2 revolutions per minute so as to be surrounded by the test substance as a whole. The force required for this is measured as torque and corresponds to each viscosity. The sample is generally preheated to 100 °C for 1 minute and the measurement continues for a further 4 minutes while keeping the temperature constant. The viscosity is reported together with each test condition, for example ML(1+4)100 °C (Mooney viscosity, rotor size L, preheating time and test time in minutes, test temperature).

[0130] The rheometer (Barkometer) used and scorch / full vulcanization time Measure the MDR (Moving Die Rheometer) vulcanization profile and associated analysis data using an MDR 2000 Monsanto rheometer in accordance with ASTM D5289-95.

[0131] The scorch time (t5) is the time at which 5% of the rubber is crosslinked. The selected temperature was 160 °C.

[0132] The complete vulcanization time (t95) is the time at which 95% of the rubber is crosslinked. The selected temperature was 160 °C.

[0133] The value of delta S’ is the difference between the maximum and minimum values of the rheometer curve, thus S max -S min is calculated from.

[0134] Determination of elongation at break, tensile strength, 300 modulus These measurements were carried out in accordance with DIN 53504 (tensile test, S2 rod, 5 measurements).

[0135] Shore A hardness Measurement of the hardness (Shore A) at 23 °C in accordance with DIN 53505 (3 measurements).

[0136] Resilience Measurement of resilience at 23 °C in accordance with DIN 53512 (3 measurements).

[0137] Determination of DIN abrasion The simplest way to determine abrasive wear is the so-called DIN abrasion in accordance with ASTM D5963. A test piece made of the elastomer to be tested is passed over a test sanding arc on a rotating cylinder with a constant pressing force and a constant speed (40 min-1) over a specified friction path (40 m). Subsequently, the reduction of the material represented in mm 3 is determined.

[0138] Determination of loss factor The loss factor tanδ was determined by dynamic attenuation according to DIN EN ISO 6721-1 at a measuring frequency of 60 °C and 10 Hz.

[0139]

Table 3

[0140] Conclusion: Surprisingly, in combination with unchanged or improved further mechanical properties, the rubber mixtures according to the invention according to Examples 1 and 2 achieve a shorter complete vulcanization time (t95), a longer scorch time (t5) and a significantly lower loss factor tanδ and a significantly lower DIN abrasion at 60 °C compared to the rubber mixture reference according to the prior art.

Claims

1. - At least one functionalized synthetic rubber of 50 to 100 phr, preferably functionalized BR rubber and / or functionalized SBR rubber, - At least one natural rubber and / or non-functionalized synthetic rubber of 0 to 50 phr, - At least one hydroxyl-containing oxide filler of 0.1 to 250 phr, - At least one carbon black of 0 to 120 phr, preferably 0.1 to 100 phr, - At least one crosslinking agent selected from the group of preferably sulfur donors and / or sulfur of 0.1 to 20 phr, and At least one ethoxylated compound of formula (I) of 0.5 to 10 phr RO(CH ２ CH ２ O) ｘ H (I), (wherein R represents alkyl, where the alkyl may be branched or unbranched, and x represents a rational number from 1 to 25) A rubber mixture containing.

2. R is C １ ~C ２０ -alkyl, preferably C ５ ~C １７ -alkyl, particularly preferably C １０ ~C １５ -alkyl, very particularly preferably iso-C １３ -alkyl, very very particularly preferably iso-C １３ H ２７ The rubber mixture according to claim 1, characterized in that it represents

3. The rubber mixture according to claim 1 or 2, characterized in that x represents a rational number from 2 to 22, preferably from 4 to 20.

4. The rubber mixture according to any one of claims 1 to 3, characterized in that the at least one functionalized synthetic rubber is selected from the group consisting of functionalized SBR rubber, functionalized BR rubber and functionalized IR rubber, preferably functionalized SBR rubber and functionalized BR rubber.

5. The rubber mixture according to any one of claims 1 to 4, characterized in that the at least one functionalized synthetic rubber is substituted by one or more functional groups selected from carboxyl group, mercaptan group, alkoxysilane group, siloxane group, hydroxyl group, ethoxy group, epoxy group, amino group, phthalocyanine group, silane-sulfide group and metal atom-containing group at the main chain and / or the terminal group, preferably selected from mercaptan group, alkoxysilane group and hydroxyl group, particularly preferably selected from mercaptan group and alkoxysilane group.

6. The rubber mixture according to any one of claims 1 to 5, characterized in that the at least one hydroxyl-containing oxide filler is selected from the group consisting of silica, synthetic silicate and natural silicate, and is present in the rubber mixture in an amount of 0.1 to 250 phr, preferably 20 to 200 phr, particularly preferably 25 to 180 phr, very particularly preferably 30 to 160 phr.

7. The rubber mixture according to any one of claims 1 to 6, characterized by containing at least one crosslinking agent from the group of sulfur and sulfur donors in an amount of 0.5 to 10 phr, preferably 1.0 to 8 phr and particularly preferably 1 to 4 phr.

8. The rubber mixture according to any one of claims 1 to 7, characterized by containing at least one reinforcing additive from the group of sulfur-containing organic silanes, particularly sulfur-containing silanes containing an alkoxysilyl group and particularly preferably sulfur-containing organic silanes containing a trialkoxysilyl group.

9. - At least one functionalized synthetic rubber of 70 to 100 phr, preferably functionalized BR rubber and / or functionalized SBR rubber, - At least one natural rubber and / or non-functionalized synthetic rubber of 0 to 30 phr, - At least one hydroxyl-containing oxide filler of 20 to 200 phr, - At least one carbon black of 0.1 to 120 phr, preferably 0.1 to 100 phr, - At least one crosslinking agent selected preferably from the group of sulfur donors and / or sulfur in an amount of 0.5 to 10 phr, - Zinc oxide of 0.1 to 10 phr, - At least one vulcanization accelerator from the group of sulfenamides in an amount of 0.5 to 10 phr, - At least one secondary accelerator of 0.1 to 10.0 phr, - At least one reinforcing additive from the group of sulfur-containing silanes in an amount of 0.5 to 15 phr, - Rubber auxiliaries of 0.1 to 30 phr and - 1 to 15 phr of at least one ethoxylated compound of formula (I) The rubber mixture according to claim 1, characterized by containing the above.

10. A process for producing a rubber mixture according to the invention according to any one of claims 1 to 9, characterized in that the respective components are mixed in a mixing process.

11. Use of the rubber mixture according to any one of claims 1 to 9 for producing vulcanizates and all types of rubber shaped articles, particularly for producing tires and tire parts.

12. A vulcanizate obtained by vulcanizing at least one rubber mixture according to any one of claims 1 to 9, preferably at a temperature of 120 °C to 200 °C.

13. A vehicle tire characterized by having at least one vulcanizate according to claim 12.

14. At vulcanization temperatures of 120°C to 200°C, for producing a vulcanizate having low rolling resistance from a sulfur-vulcanizable rubber mixture, at least one ethoxylated compound of formula (I) in an amount of in particular 0.5 to 20 phr, particularly preferably 1.0 to 15.0 phr RO(CH ２ CH ２ O) ｘ H (I), (wherein R represents alkyl, where the alkyl may be branched or unbranched, and x represents a rational number from 1 to 25), and the use of at least one functionalized synthetic rubber in an amount of in particular 50 to 100 phr, particularly preferably 70 to 100 phr.

15. A bonding mixture comprising at least one rubber mixture according to any one of claims 1 to 9 and at least one binder based on resorcinol, formaldehyde and silica.

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